20 - 用户指定分辨率
Laocontour - 用于插值的等高线
Elev-等高线cover的属性表中，表示高程属性的字段名 Laostream-河流网络cover Enforce on-清除凹陷
二、基于电源数据生成DEM的插值方法 数据源：GPS测点，地形图网格采点等。 Arc: items pntcov.pat
COLUMN ITEMNAME WIDTH OUTPUT TYPE N.DEC ALTERNATENAME
9 PNTCOV# 4 5 B 13 PNTCOV-ID 4 5 B 21 YIELD 8 8 F 6 29 X_COORD 8 10 F 3 37 Y_COORD 8 11 F 3 Arc: q
1) 反距离加权插值法 IDW
反距离加权法中距离的指数，指数越小表面越光滑，常用范围为0.5~3,缺省为2。 Arc: grid
Grid: pntgrdidw=idw(pntcov,yield,#,2,sample,#,#,2.5) Running ... 100%
Grid:
2) 样条插值法
Tension表示张力样条插值法，Regularized表示规则样条插值法 Grid: pntgrdspline = spline(pntcov,yield,tension,#,#,2.5) Running ... 100% Grid:
3) 克吕格插值法
Kriging方法包括普通Kriging ( SPHERICAL, CIRCULAR,
EXPONENTIAL, GAUSSIAN, LINEAR)和泛Kriging(UNIVERSAL1 UNIVERSAL2) Grid: pntcovkriging =
kriging(pntcov,yield,#,#,#,SPHERICAL,SAMPLE,#,#,2.5) Estimating semi-variogram ...
Ordinary Kriging with the Following Model(s): SPHERICAL c0 = 0.003 c = 0.004 a = 208.237 sill = 0.007
Interpolating grid ... 100% Grid:
三．常用DEM数据资源 GTOPO30 DEM 1) GTOPO30数据特点
由USGS EROS完成于1996年, 历时3年
GTOPO30数据源：DTM, DCW(VMAP0), USGS 1 degree DEM 覆盖全球陆地 90N – 90S, 小于1平方公里小岛屿忽略 数据库大小：1.74 Giga (行21600 列43200) 分辨率: 30 arc seconds (约1公里) 高程范围: -407 ~ 8,752 meter
数据格式：16bit二进制格式bil，MSB - big endian 2) Vertical accuracy (meters)
Source L.E. at 90% RMSE Estimation method ------ -------------------------- ----------------- DTED 30 18 product specification DCW 160 97 calculated vs. DTED USGS DEM 30 18 product specification
AMS maps 250 152 estimated from 500-meter interval IMW maps 50 30 estimated from 100-meter interval Peru map 500 304 estimated from 1,000-meter interval N.Z. DEM 15 9 estimated from 100-foot interval ADD highly variab wide le range of scales and intervals 3) GTOPO30数据的获取
整个数据库分为33 tiles，中国占据4 tiles： E60N90 E100N90
E60N40 E100N40
Lat Lon Elev
Tile Min Max Min Max Min Max Mean Std.Dev. ------- ------- ------- ---------------------
E060N90 40 90 60 100 -152 7169 509 698 E100N90 40 90 100 140 1 3877 597 455 E060N40 -10 40 60 100 1 8752 1804 1892 E100N40 -10 40 100 140 -40 7213 692 910 4) GTOPO30数据文件解释 (以E100N40为例) FileName Contents ----------- ---------------
E100N40.DEM digital elevation model (BIP/BIL/BSQ) E100N40.HDR header file for DEM E100N40.DMW world file E100N40.STX statistics file
E100N40.PRJ projection information file E100N40.GIF shaded relief image E100N40.SRC source map
E100N40.SCH header file for source map 5) SRTM DEM数据的处理与拼接 #(ASCII DEM情况下, 投影参数手工定义) Arc: projectdefine grid n040e116
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